Adverse human health effects due to occupational and environmental exposure to nanomaterials are a major concern and a potential threat to their successful commercialization and biomedical applications. Realization of their commercial potential will require a better understanding of the interactions of nanomaterials with biological systems and the development of new strategies to manage human health risk. Manufactured carbon nanomaterials are highly variable with respect to chemical and physical properties, state of aggregation, and purity. Toxicological screening is urgently needed to identify potentially hazardous nanomaterials;however, their wide variability and unique properties complicate interpretation of traditional in vitro and in vivo toxicity assays. An interdisciplinary research team at Brown University including a materials scientist, a toxicologic pathologist, and a molecular biologist has developed a panel of novel nanomaterials and innovative approaches for nanotoxicology assays. This panel of model nanomaterials will be expanded to include selected commercial materials subjected to rigorous characterization of lexicologically relevant materials properties. Novel synthesis and characterization methods will be used to carry out systematic studies (Specific Aims 1 and 2) that reveal the chemical (surface state, metals bioavailability, biopersistence), structural (size, shape, elasticity), and superstructural (aggregate size and shape) basis of carbon nanomaterial toxicity. This team will develop and validate a unique platform for cellular assays in 3- dimensional culture using formation of granulomas, persistent macrophage activation, and fibrosis as pathologic endpoints (Specific Aim 3). This platform will incorporate post-exposure characterization of nanomaterials in parallel with an acellular assay to assess biopersistence and aggregation state in simulated intracellular environments (Specific Aim 4). A cytokine expression profile will be developed to predict toxicity of carbon nanomaterials relative to standard reference materials (Specific Aim 5). It is anticipated that this validated toxicologic screening assay will provide an alternative to chronic rodent inhalation assays at lower cost and reduced burden of animal testing. Identification of specific chemical and physical properties of nanomaterials responsible for cellular toxicity will enable development of manufacturing methods and post processing steps to eliminate intrinsic toxicity.